Cathode assemblies and sputtering systems

ABSTRACT

A cathode assembly for a magnetron sputtering system includes a target comprising sputterable material having an at least partially exposed, substantially planar sputtering or erosion surface and a target support configured to support and move the target during sputtering. In certain exemplary embodiments the cathode assembly further comprises a magnetic field source, e.g., a magnet array behind the target. The target support is configured to move the sputtering surface of the target by rotating or spinning the target in the plane of the sputtering surface, moving the target linearly back-and-forth or otherwise. The target support is configured to move the target relative to the magnetic field source, which may be stationary during sputtering, e.g., relative to the cathode assembly and vacuum chamber in which the sputtering is performed. A sputtering system including such a cathode assembly also is provided. A method of sputtering is further provided, employing such a cathode assembly.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/630,940 (pending), filed Dec. 4, 2009, which claims the priority ofU.S. Provisional Application No. 61/120,646, filed Dec. 8, 2008, each ofwhich is hereby incorporated herein by reference in its entirety for allpurposes.

FIELD OF THE INVENTION

The inventive subject matter disclosed herein involves a cathodeassembly for a sputtering system, and in particular, a cathode assemblyhaving a movable target. The inventive subject matter further involvessputtering systems comprising a cathode assembly having a movabletarget.

BACKGROUND

A sputtering process deposits a thin film of target material on asubstrate by dislodging small particles or atoms from a target, whichcoat the substrate. Magnetic fields have been used to enhance thesputtering process. For example, as disclosed in U.S. Pat. No. 4,166,018to Chapin, titled “Sputtering Process and Apparatus,” which isincorporated herein by reference in its entirety, in a conventionalvacuum sputtering process a substrate is placed in front of a sputteringcathode in a vacuum chamber. The sputtering cathode includes asubstantially planar target formed of the target material. The pressurein the chamber is reduced and then, optionally, back filled with areactive or inert sputtering gas. A negative voltage is applied toproduce a plasma discharge from the target surface. The plasma dischargeis intensified by magnets located behind the target to produce a closedloop magnetic field over the target surface.

Over time, the target becomes depleted. Unfortunately, uneven depletionof the target, e.g., grooving of the target surface, can adverselyimpact the quality of the film deposited on the substrate. It can alsoresult in inefficient use of the target, with consequent cost penalties.One cause of uneven depletion of the target surface is that erosion ishighest at regions where the magnetic field lines are tangent to thetarget surface. Thus, it is known in the art to rotate an array ofmagnets behind the target, to develop more uniform erosion of the targetsurface. U.S. Pat. No. 4,995,958 to Anderson et al., titled “SputteringApparatus with a Rotating Magnet Array having a Geometry for SpecifiedTarget Erosion Profile,” U.S. Pat. No. 5,248,402 to Ballentine et al.,titled “Apple-Shaped Magnetron for Sputtering System,” U.S. Pat. No.5,830,327 to Kolenkow, titled “Methods and Apparatus for Sputtering withRotating Magnet Sputter Sources,” and U.S. Pat. No. 6,258,217 toRichards et al., titled “Rotating Magnet Array and Sputter Source,” eachof which is incorporated herein by reference in its entirety, disclosevarious cathode assemblies for sputtering systems having a magnet arraythat rotates behind the plane of a circular flat target. It is alsoknown to optimize the shape of the magnet array, either symmetric orasymmetric with respect to the axis of rotation, to further reduceuneven erosion of target surface.

Rotating magnet arrays create a moving deposition erosion zone at thestationary surface of the target and, correspondingly, a movingdeposition plume from the surface of the target. This may result in anuneven deposition pattern on the substrate and a reduced ability todeposit precision films. This may be particularly problematic forcertain sputtering processes, such as long-throw sputtering orlong-throw reactive sputtering.

Further, the areas on the target that are not being eroded are subjectto back coating and reactive gas poisoning. This can result in arcingand/or a reduced deposition rate. With moving magnets, it becomesproblematic to cover areas of the target that are not getting erodedwith shields that could prevent back-scattered coating material orreactive gases from building up a layer of undesirable material on thetarget surface. Typically, with moving magnets, the bigger the ratio ofthe target area to the magnet area, the worse these problems can become.

There is a need in the sputtering art to reduce non-uniform erosion ofthe target and provide improved target utilization. There is a furtherneed to provide improved deposition rates and improved uniformity of thedeposited films when depositing onto large-area substrates.

SUMMARY

In accordance with one aspect, a cathode assembly for a magnetronsputtering system comprises, in combination, a target and a targetsupport configured to support and move the target. The target comprisesa sputterable material having an at least partially exposed planarsputtering surface. In at least certain exemplary embodiments thecathode assembly further comprises a magnetic field source. The magneticfield source may comprise a magnet array. In certain exemplaryembodiments such magnet array is behind the target, i.e., on the side ofthe target opposite the erosion or sputtering surface (those terms beingused interchangeably here and in the appended claims), e.g., oppositethe side that will face the substrate to be coated during use of thecathode assembly in a sputtering operation. The magnet array may, forexample, be a two-dimensional array in a plane generally parallel to theplanar erosion surface or planar sputtering surface of the target.Optionally, the cathode assembly also has a magnet array supportconfigured to support the magnet array, e.g., in a stationary positionduring movement of the target in a vacuum chamber during sputtering. Incertain exemplary embodiments the target support of the cathode assemblycomprises a frame. Optionally, in embodiments having a magnet array andsuch frame, the magnet array may be supported within the frame behindthe target.

In certain exemplary embodiments the cathode assembly further comprisesa mounting surface for fixed-position mounting to a vacuum chamber toposition the cathode assembly at least partially within the vacuumchamber. The target support of the cathode assemblies disclosed heretypically are operative to move the target relative to the mountingsurface during sputtering. In certain exemplary embodiments the planarsputtering surface of the target is circular and the target support isoperative to rotate the target in a vacuum chamber during sputtering,that is, to spin the target on an axis not parallel to, e.g., generallyperpendicular to, the target's planar sputtering surface. In certainexemplary embodiments the target support is operative to orbit androtate the target in a vacuum chamber during sputtering, wherein theorbiting and rotating are in generally the same plane. It should beunderstood that use of the term “generally” and similar terms here andin the appended claims is intended to mean approximately or within theconstraints of sensible, commercial engineering objectives, costs andcapabilities. In other exemplary embodiments the target support isoperative to move the target back and forth in the plane of the planarsputtering surface in a vacuum chamber during sputtering. In someembodiments the target support is operative to provide compound movementof the target, e.g., a combination of lateral and spinning movement,etc. In certain exemplary embodiments the cathode assembly is operativeto dither the magnet assembly during sputtering.

In accordance with another aspect, a cathode assembly for a sputteringsystem includes a target support configured to support a target having aplanar erosion surface. The target defines a target axis that issubstantially perpendicular to the planar erosion surface of the target.The target support is configured to rotate the target around the targetaxis. The cathode assembly may further include a magnetic field source,wherein the target support is configured to move the target relative tothe magnetic field source.

In accordance with another aspect, a cathode assembly for a sputteringsystem includes a target support configured to support a target havingan erosion surface and a magnetic field source. The target support isconfigured to rotate the target around an axis that is not parallel tothe erosion surface of the target. The target support is furtherconfigured to move the target relative to the magnetic field source.

In accordance with another aspect, a cathode assembly for a sputteringsystem having a target support and a magnet array. The magnet arrayincludes a plurality of magnets arranged in a substantiallytwo-dimensional planar array and defining a substantiallytwo-dimensional magnet plane. The target support is configured to move asubstantially planar target in a plane substantially parallel to thesubstantially two-dimensional magnet plane.

Additionally, another aspect of the present invention is directed tomagnetron sputtering systems comprising a vacuum chamber, a cathodeassembly in accordance with the disclosure above, mounted to the vacuumchamber, and a magnetic field source for the erosion surface. At leastcertain exemplary embodiments of the magnetron sputtering systemsdisclosed here include a vacuum chamber having a mount for a workpiece,i.e., a substrate to be coated, a cathode assembly comprising a targetof sputterable material having an at least partially exposed planarsputtering surface and a target support configured to support and movethe target in the vacuum chamber during sputtering, and a magnetic fieldsource. The target support is configured to move the target relative tothe chamber, and typically relative to the magnetic field produced bythe magnetic field source. The target support in certain exemplaryembodiments is configured to rotate the target around an axis that isnot parallel to the erosion surface of the target, e.g., perpendicularto that surface. The magnetic field source may include a plurality ofmagnets arranged in a substantially two-dimensional array.

In at least certain exemplary embodiments of the magnetron sputteringsystems disclosed here, an energy source or power source (e.g. RF, DC,pulsed DC, dual alternating cathode DC) is provided to maintain thesputtering plasma during sputtering, typically during operation of themagnetron sputtering system for deposition of material from a targetonto a substrate in a vacuum chamber. It will be understood by thoseskilled in the art, given the benefit of this disclosure, that themagnetron sputtering systems typically will be used in a vacuum chamber.It can be mounted entirely inside or through the wall of a vacuumchamber. Typically, feedthroughs can be used to deliver power, coolingwater, etc. to the magnetron sputtering systems or otherwise into thechamber. In certain exemplary embodiments cooling liquid is used forcooling the target. For example, cooling liquid lines can be used tocirculate water or other cooling liquid to cool the target. In certainexemplary embodiments cooling liquid is circulated to a thermallyconductive backing plate for the target, e.g., a metal plate in thermalcontact with the target. Couplings along such cooling line(s) must beliquid-tight and accommodate the sliding and/or spinning movement of thetarget. In certain exemplary embodiments of the magnetron sputteringsystems disclosed here, a power source is provided to actuate the drivemechanism to move the substantially planar sputtering surface of thetarget during sputtering.

Another aspect of the present invention is directed to a method forsputtering. In accordance with this aspect, magnetron sputtering methodsare provided for deposition of target material on a substrate. Themagnetron sputtering methods according to this aspect comprise providinga vacuum chamber with a workpiece mount for mounting a substrate withinthe chamber during sputtering. A cathode assembly according to thedisclosure above is mounted to the vacuum chamber. A workpiece orsubstrate is mounted in the chamber via the workpiece mount. To sputtertarget material to deposit onto the substrate, the vacuum chamber is atleast partially evacuated and then a sputtering gas or plasma is fedinto the vacuum chamber. Power is supplied to the cathode assembly toinitiate and maintain a sputtering plasma and to move the substantiallyplanar sputtering surface of the target during sputtering. In certainexemplary embodiments the cathode assembly comprises a drive mechanismto rotate the sputtering surface, typically in the plane of thesputtering surface, e.g., about an axis that is perpendicular to thesubstantially planar surface of the target. In certain exemplaryembodiments the drive mechanism moves the substantially planarsputtering surface of the target relative to the magnet array, which maybe stationary, i.e., stationary relative to the chamber, the sputteringplume, the substrate (ignoring any spinning motion of the substrate),the workpiece mount and the like. Optionally, in addition to motion ofthe target's sputtering surface, the magnetic field may be in motionduring sputtering, e.g., by oscillating a magnet array proving all orsome of the magnetic field. The sputtering may in certain exemplaryembodiments be long-throw sputtering of target material onto thesubstrate.

The sputtering methods disclosed here in accordance with certainexemplary embodiments include providing a cathode assembly having amagnet array and a movable target support connectable to a drivemechanism. The magnet array optionally includes a plurality of magnetsarranged in a substantially planar two-dimensional array. Such methodsfurther include providing a substrate, providing a sputtering gas, andsupplying power to the cathode assembly. The movable target support isdriven to move the substantially planar surface of the target relativeto the substantially planar two-dimensional array of the plurality ofmagnets.

Those of ordinary skill in the art will recognize that the cathodeassemblies and sputtering systems and methods disclosed here presentsignificant technical and commercial advantages. Likewise, those ofordinary skill in the art will recognize that innumerable modificationscan be made and other features are aspect added without departing fromthe principles disclosed here.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing Summary, as well as the following Detailed Description,will be better understood when read in conjunction with the accompanyingdrawings.

FIG. 1 is a schematic illustration of a sputtering system in accordancewith certain exemplary embodiments of the present disclosure;

FIG. 2 is a cross-sectional side view of a cathode assembly inaccordance with an exemplary embodiment of the present disclosure;

FIG. 3 is an external perspective view of a cathode assembly inaccordance with the exemplary embodiment of FIG. 2;

FIG. 4 is a schematic illustration of a sputtering system in accordancewith other exemplary embodiments of the present disclosure;

FIG. 5 is a schematic illustration of a sputtering system in accordancewith even other exemplary embodiments of the present disclosure; and

FIG. 6 is schematic illustration of an alternative embodiment of atarget and magnetic array unit of the sputtering system of FIG. 1;

FIG. 6A is a plan view of a round or circular magnet array (that is,comprising magnets laid out in a round or circular pattern in a planeparallel to the planar sputtering surface of the target) suitable for atleast certain exemplary embodiments of the cathode assemblies andsputtering systems disclosed here.

FIG. 6B is a sectional elevation taken through line A-A of FIG. 6A.

FIG. 7A is a plan view of a non-round, specifically an apple-shaped orcardioid magnet array (that is, comprising magnets laid out in acardioid pattern in a plane parallel to the planar sputtering surface ofthe target) suitable for at least certain exemplary embodiments of thecathode assemblies and sputtering systems disclosed here.

FIG. 7B is a sectional elevation taken through line A-A of FIG. 7A.

FIG. 8 is a schematic illustration of an alternative embodiment of asputtering system with a plurality of cathode assemblies.

The figures referred to above are not drawn necessarily to scale, shouldbe understood to provide a representation of particular aspects of theinvention, and may be merely conceptual in nature and illustrative ofthe principles involved. Some features of the cathode assembly andsputtering system depicted in the drawings have been enlarged ordistorted relative to others to facilitate explanation andunderstanding. The same reference numbers are used in the drawings forsimilar or identical components and features shown in variousalternative aspects. Cathode assemblies and sputtering systems asdisclosed herein would have configurations and components determined, inpart, by the intended application and environment in which they areused.

DETAILED DESCRIPTION OF CERTAIN EXEMPLARY EMBODIMENTS

The basic sputtering processes are well understood for depositing targetmaterials on substrates. The teachings presented herein with respect tocathode assemblies, magnetron sputtering systems and methods may beapplied to any sputtering process and apparatus that uses magneticfields to enhance the sputter deposition process. Further it should beunderstood the present disclosure contemplates that all discloseddetails, including optional and alternative features and details and thelike, may be used all together, in any subset, and in any operativecombination or permutation.

Reference here to the disclosed cathode assemblies of the magnetronsputtering systems being mounted to or on or in a vacuum chamber shouldbe understood to mean mounting on (i.e., wholly or partially on) thechamber, in (i.e., wholly or partially in) the chamber, to the chamber,within (i.e., wholly or partially within) the chamber, and/or the like.Thus, with the cathode assembly mounted to a vacuum chamber, certaincomponents or portions of components or parts of the cathode assemblymay be wholly or partly inside the chamber, some may extend through thewall of the chamber, some may be wholly or partly outside the chamber,etc. As disclosed above, the disclosed cathode assemblies in at leastcertain exemplary embodiments have a mounting surface for fixed-positionmounting to a vacuum chamber. As used here, the term “fixed-positionmounting to a vacuum chamber” means that, when a cathode assemblyaccording to such embodiments are mounted to a chamber, the mountingsurface of the cathode assembly is fixed or immovable relative to themain body of the chamber, e.g., relative to a chamber wall to which itis bolted or otherwise secured. As a non-limiting example, if thecathode assembly is mounted at a hole or port in the outer wall of avacuum chamber, the mounting surface may be in fixed, surface-to-surfacecontact with the inner and/or outer surface of the chamber wall. Certainexemplary embodiments of the cathode assemblies disclosed here will havemore than one mounting surface and optionally more than one mountingsurface with fixed-position mounting to a vacuum chamber.

In typical operations employing a magnetron sputtering system comprisinga cathode assembly in accordance with the present disclosure mounted toa vacuum chamber, the cathode assembly is at least partially within thevacuum chamber. The target in a typical sputtering operation will bewithin the vacuum chamber or in communication with the main portion ofthe chamber holding the substrate and, as disclosed above, will besupported for rotation or other movement during sputtering. In thoseembodiments having a mounting surface as discussed immediately above,the target support is operative to move the target relative to suchmounting surface. In that regard, it should be understood that referencehere to the target being moveably supported by the target support, andsimilar descriptions, such as that the target support is operative tomove the target, mean that the target support is operative to move thetarget during sputtering, i.e., during use of the magnetron sputteringsystem in a sputtering operation, typically in a vacuum chamber. Thatis, the target support is operative to move the target relative to theplasma plume that will be created by operation of the magnetronsputtering system during sputtering, or relative to the wall(s) of thechamber, or relative to the main body of the chamber or to the mainstructure or superstructure of the cathode assembly, or to all of them.In typical embodiments, the superstructure of the cathode assembly ismounted to a chamber wall in fixed position to the chamber, and thetarget support is operative to move the target relative to the plasmaplume, chamber and superstructure of the cathode assembly.

Referring now to the drawings, FIG. 1 is a schematic view of sputteringsystem 100 according to one non-limiting embodiment of the invention.Sputtering system 100 includes a vacuum chamber 110 having a sputteringgas inlet 112, a work piece holder 120 and a cathode assembly 200.Cathode assembly 200 and work piece holder 120 are located within vacuumchamber 110. A substrate (S) is mounted to work piece holder 120.Typically, a sputtering system also includes a vacuum pump, a powersource, and one or more sputtering gas sources (not shown).

FIG. 2 is a cross-section side view of cathode assembly 200 according tocertain aspects of the invention. Cathode assembly 200 includes amagnetic field source, such as magnetic array unit 210, and a targetsupport 220. Referring also to FIG. 3, cathode assembly 200 typicallyincludes a housing 202, a means for cooling the cathode assembly 204 anda dark space shield 206.

As presented in FIGS. 1 and 2, target support 220 holds target 222within a frame 224.

Target 222, which may be formed of one or more target materials, is asubstantially planar target having a planar top surface 223. Top surface223 is an erosion surface that supplies the material to be deposited onsubstrate (S). The target material that is sputtered may comprise anysuitable material as would be apparent to those of ordinary skill in theart. Target 222 may be bonded or otherwise attached to a target backingplate. Reference here to the sputtering or erosion surface of the targetbeing planar or the like means that it is generally flat or lying in aplane. In that regard, it will be understood by those of ordinary skillin the art given the benefit of this disclosure, that the sputteringsurface will, of course, not be removed perfectly evenly duringsputtering and, so will develop an erosion pattern during sputtering.The sputtering surface should be understood to be planar, as that termis used here (alternatively referred to here and in the claims, eitherbefore or after such erosion pattern develops, as being generallyplanar), notwithstanding such erosion pattern. Target support 220further includes a hollow shaft 226 extending between frame 224 anddrive mechanism 230.

Magnetic array unit 210 can be any suitable source of magnetic fieldlines as would be apparent to a person of ordinary skill in the art,given the benefit of the present disclosure. According to certainexemplary embodiments of the present invention, magnetic array unit 210includes one or more permanent magnets 211 arranged in a substantiallytwo-dimensional array. A substantially two-dimensional array of magnetsincludes a plurality of magnets extending in a first direction and aplurality of magnets extending in a second direction. The array issubstantially two-dimensional even if some of the magnets do not lieprecisely in the plane. Further, the first and second directions may belinear or curvilinear. When the first and second directions are bothlinear, the two-dimensional array is planar. When at least one of thefirst and second directions is curvilinear, the two-dimensional array isno longer planar, but curves out of the plane. As shown in theembodiment of FIG. 2, the substantially two-dimensional array is planar,i.e. the magnets lie substantially in a flat plane. Further, thesubstantially two-dimensional planar array lies parallel to top surface223 of target 222. A central shaft 212 supports magnetic array unit 210.

According to certain exemplary embodiments of the invention, as shown inFIGS. 1 and 2, magnetic array unit 210 is stationary relative to vacuumchamber 110 and target support 220 is movable relative to vacuum chamber110. A drive mechanism 230 is drivably connected to target support 220.In operation of such embodiments, drive mechanism 230 causes shaft 226,frame 224 and target 222 to rotate around axis 225 (see arrow A in FIG.1). Axis 225 is substantially perpendicular to the plane of planar topsurface 223.

According to certain exemplary embodiments of the invention, as shown inFIG. 4, magnet array 210 moves relative to axis 225 of target 222. As anon-limiting example, magnet array 210 may oscillate radially (back andforth in the direction of arrow B) from axis 225, in the plane of themagnetic array, using relative small displacements. This may serve tofurther smooth out any erosion pattern formed on erosion surface 223. Asanother example, magnet array 210 may move in the plane of the magnetarray in an X- or Y-direction (or both an X- and Y-direction) relativeto axis 225.

In another embodiment, as shown in FIG. 6, target 222 isconically-shaped. Magnetic field source 210 is located within the coneof target 222. In an exemplary embodiment, magnetic field source has atwo-dimensional, curvilinear, array of magnets, i.e., the array ofmagnets essentially follows the curve of the cone. Conically-shapedtarget 222 may rotate around an axis 227 that extends through the centerof the cone (see arrow A). Magnetic field source 210 may be stationaryor may oscillate slightly parallel to the surface 223 of the cone (seearrow B).

Referring now to FIGS. 6A and 6B, a round or circular magnet array isshown that is suitable for at least certain exemplary embodiments of thecathode assemblies and sputtering systems disclosed here. The magnetarray 240 has magnets 242 laid out in a round or circular pattern in aplane, specifically, a plane 243 parallel to the planar sputteringsurface of the target. The magnets include outer ring 242A and innerring 242B. The magnets of both the inner and outer rings are centeredabout point “C” on a support plate 241.

Referring now to FIGS. 7A and 7B, a non-circular magnet array 244 isshown, specifically, an apple-shaped or cardioid shaped array that issuitable for at least certain exemplary embodiments of the cathodeassemblies and sputtering systems disclosed here. The magnet array 244has magnets 246 laid out in such cardioid pattern in a plane 247parallel to the planar sputtering surface of the target. The magnetsinclude outer (non-circular) ring 246A and inner (non-circular) ring246B. The magnets are positioned on a support plate 248.

In yet other exemplary embodiments, as best shown in FIG. 5, targetsupport 220 may move linearly, parallel to the plane of surface 223 (seearrow C). This may be particularly useful if the planar target issubstantially rectangular or elongate. In such instance, the widthdimension of target 222 may be substantially the same as the widthdimension of magnetic array unit 210, while the length dimension oftarget 222 may be considerably longer than the length dimension ofmagnetic array unit 210. Thus, the rectangular or elongate target 222,may be slidably driven back-and-forth in its length direction overmagnetic array unit 210 in order to develop a substantially uniformerosion profile while maintaining a stationary deposition plume. Inother exemplary embodiments, target support 220 may move by acombination of movements within the plane. For example, target support220 may move linearly in a first direction and also rotate round an axisperpendicular to the plane of top surface 223. Alternatively, targetsupport 220 may move linearly in the plane of top surface 223 in twomutually orthogonal directions.

The sputtering processes disclosed here, according to an aspect of theinvention, includes placing a cathode assembly 200 having a magnet array210 and a target support 220 in a vacuum chamber 110. The target support220 is connected to drive mechanism 230. The magnet array 210 includes aplurality of magnets arranged in a substantially planar two-dimensionalarray. Target support 220 includes a target 222 having a substantiallyplanar erosion surface 223. A substrate, upon which material from thetarget is to be deposited, is placed in the vacuum chamber. A vacuum isdrawn in the vacuum chamber and an inert sputtering gas, a reactivesputtering gas, or a combination of inert and reactive sputtering gasesare introduced into the chamber. An electrical potential is developedacross the substrate and the cathode assembly. Power is supplied tocathode assembly to drive the drive mechanism and thereby move targetsupport 220 relative to the substantially planar two-dimensional arrayof the plurality of magnets of the magnet field source 210.

During sputtering, the ion density of the plasma formed will be higherin the area near magnetic array unit 210 as compared to the plasma inthe area of the target remote from magnetic array unit 210. With anincreased ion density, material is sputtered from the target at a higherrate. For certain applications requiring improved uniformity, thecathode assembly may be spaced a greater distance from the substrate(S), forming a “long-throw” deposition plume. The substrate may be spunabout its axis to further improve uniformity. As an example of along-throw sputtering process, cathode assembly 200 may be spaced fromthe substrate (S) by about 200 mm to about 350 mm in both dimensions ofoffset and displacement.

According to the exemplary embodiments disclosed herein, the area of thetarget's erosion surface can be made almost arbitrarily large. Thisreduces the amount of etch or erosion from each deposition cycle for anygiven area of the target surface. Further, large targets provide anincreased inventory of target material. It is expected that the ratio ofthe area of the planar erosion surface of the target to the area of thefootprint of the magnetic field source would typically be greater thanapproximately 3.0, and that the ratio could easily be greater thanapproximately 4.0 or 5.0.

Due to the improved erosion profile, it is expected that the utilizationof the target could exceed 50% or even 60%. In certain instances, it isexpected that utilization of the target in a commercially efficientsputtering operation could range from approximately 60% to approximately85%.

In the embodiment of a sputtering system schematically shown in FIG. 1,a single cathode assembly is shown. It is to be understood that aplurality of cathode assemblies may be positioned within vacuum chamber110, as seen in FIG. 8. Further it should be understood that the cathodeassembly disclosed herein may have utility in other sputtering systemconfigurations, including those sputtering systems configured to processlarge area substrates.

Those of ordinary skill in the art will recognize that the sputteringsystems and cathode assemblies disclosed herein present significanttechnical and commercial advantages. The preceding detailed descriptionof certain exemplary embodiments was not intended to limit the scope ofthe disclosure to merely those exemplary embodiments, but rather to beillustrative of such scope. Further, all examples, whether demarcated bythe terms “for example,” “such as,” “including,” “etc.” or otheritemizing terms, are meant to be non-limiting examples, unless otherwisestated or obvious from the context of the specification. Although thepresent invention has been described above in terms of certain exemplaryembodiments, it should be understood that other embodiments, other uses,alterations and modifications thereof will be apparent to those skilledin the art given the benefit of this disclosure, and that suchmodifications can be made and other features added without departingfrom the principles disclosed here. Thus, it will be appreciated thatvarious modifications and alterations will be apparent from thisdisclosure to those skilled in the art, without departing from thespirit and scope of the invention as set forth in the following claims.Also, it is intended that the embodiments described above beinterchangeable, e.g. one or more elements of any of the embodiments maybe interchanged with any of the elements of any other embodiments. It isalso intended that the following claims be read as covering all suchalterations and modifications as fall within the true spirit and scopeof the invention. It should be understood that the use of a singularindefinite or definite article (e.g., “a,” “an,” “the,” etc.) in thisdisclosure and in the following claims follows the traditional approachin patents of meaning “at least one” unless in a particular instance itis quite clear from context that the term is intended in that particularinstance to mean specifically one and only one. Likewise, the term“comprising” is open ended, not excluding additional items, features,components, etc.

We claim:
 1. A DC magnetron reactive sputtering system comprising, incombination: a vacuum chamber comprising a workpiece mount for mountinga substrate within the vacuum chamber and for spinning the substrateabout an axis during sputtering, and a plurality of cathode assembliesconfigured for DC reactive sputtering, each cathode assembly comprising:a target comprising sputterable material having an at least partiallyexposed planar sputtering surface, a target support configured tosupport the target in the vacuum chamber and rotate the target relativeto the vacuum chamber about an axis fixed with respect to the vacuumchamber during sputtering, and a magnetic field source comprising amagnet array behind the target in a plane generally parallel to theplanar sputtering surface and having a central axis extendingperpendicular to a major surface of each magnet in the array, whereinthe magnet array is mounted to be substantially stationary relative tothe vacuum chamber during sputtering, wherein the cathode assembly isconfigured for long-throw sputtering of target material onto thesubstrate, and wherein the central axis extends in a directionperpendicular to the sputtering surface and at an acute angle withrespect to the axis about which the substrate spins.
 2. The DC magnetronreactive sputtering system of claim 1, wherein the target supportcomprises a frame, and the magnetic field source comprises the magnetarray supported within the frame.
 3. The DC magnetron reactivesputtering system of claim 1, further comprising a mounting surface forfixed-position mounting to the vacuum chamber to position the cathodeassembly at least partially within the vacuum chamber, wherein thetarget support is operative to move the target relative to the mountingsurface.
 4. The DC magnetron reactive sputtering system of claim 1,wherein the target support is operative to move the target back andforth during sputtering.
 5. The DC magnetron reactive sputtering systemof claim 1, wherein the target support comprises cooling liquid linesoperative to circulate cooling liquid in thermal communication with thetarget during sputtering.
 6. The DC magnetron reactive sputtering systemof claim 5, wherein the target support comprises a backing plate for thetarget, the backing plate being configured to receive cooling liquidfrom the cooling liquid lines during sputtering.
 7. The DC magnetronreactive sputtering system of claim 1, wherein the plurality of cathodeassemblies includes a pair of cathode assemblies configured for dualalternating cathode DC reactive sputtering.
 8. The DC magnetron reactivesputtering system of claim 1 wherein a ratio of an area of a planarerosion surface of the target to an area of a footprint of the magneticfield source is greater than 3.0.
 9. A DC magnetron reactive sputteringsystem comprising, in combination: a vacuum chamber; and a plurality ofcathode assemblies configured for DC reactive sputtering, each cathodeassembly comprising: a target comprising sputterable material having anat least partially exposed planar sputtering surface and defining atarget axis that is fixed with respect to the vacuum chamber and that isat an acute angle with respect to the planar sputtering surface, and atarget support configured to support the target, and to rotate thetarget about the fixed target axis during sputtering, and a magneticfield source comprising a magnet array behind the target in a planegenerally parallel to the planar sputtering surface, the magnet arrayhaving a central axis extending perpendicular to a major surface of eachmagnet in the array and being mounted to be stationary relative to thevacuum chamber during sputtering, wherein the cathode assembly isconfigured for long-throw sputtering of target material onto a substratethat spins about an axis, the axis about which the substrate spins beingat an acute angle with respect to the central axis of the magnetic fieldsource, and wherein the central axis of the magnetic field extendsperpendicular to the planar sputtering surface.
 10. The DC magnetronreactive sputtering system of claim 9, wherein a ratio of an area of theplanar sputtering surface of the target to an area of a footprint of themagnet array is greater than 3.0.
 11. The DC magnetron reactivesputtering system of claim 9, wherein the magnetic field sourcecomprises a magnet array having a plurality of magnets arranged in asubstantially two-dimensional planar array.
 12. The DC magnetronreactive sputtering system of claim 9, further comprising a shieldcovering a portion of an erosion surface of the target.
 13. The DCmagnetron reactive sputtering system of claim 12, wherein the shield hasan opening over the erosion surface that is substantially coincidentalwith the substantially two-dimensional magnet array behind the target.14. The DC magnetron reactive sputtering system of claim 9, wherein thetarget support is configured to rotate the target relative to the magnetarray around an axis substantially perpendicular to the plane of thesubstantially two-dimensional magnet array.
 15. The DC magnetronreactive sputtering system of claim 9, wherein the target supportencloses the magnet array.
 16. The DC magnetron reactive sputteringsystem of claim 9, wherein the plurality of cathode assemblies includesa pair of cathode assemblies configured for dual alternating cathode DCreactive sputtering.
 17. A DC magnetron reactive sputtering system fordeposition of target material on a workpiece, comprising, incombination: a vacuum chamber comprising a mount for a workpiece thatspins about an axis fixed with respect to the vacuum chamber, and aplurality of cathode assemblies configured for long-throw sputtering oftarget material onto the workpiece, each cathode assembly comprising: atarget of sputterable material having an at least partially exposedplanar sputtering surface, a target support configured to support androtate the target about a target axis fixed with respect to the vacuumchamber during sputtering, and a magnetic field source mounted to bestationary relative to the vacuum chamber during sputtering and having acentral axis extending perpendicular to a major surface of magnetsincluded in the magnetic field source, wherein the central axis extendsin a direction perpendicular to the sputtering surface and at an acuteangle with respect to the axis about which the workpiece spins.
 18. TheDC magnetron reactive sputtering system of claim 17, for deposition oftarget material on a workpiece, wherein the magnetic field sourcecomprises a plurality of magnets in a substantially two-dimensionalmagnet array.
 19. The DC magnetron reactive sputtering system of claim18, wherein the plurality of cathode assemblies includes a pair ofcathode assemblies configured for dual alternating cathode DC reactivesputtering.
 20. The DC magnetron reactive sputtering system of claim 18,wherein a ratio of an area of a planar erosion surface of the target toan area of a footprint of the magnetic field source is greater than 3.0.21. A DC magnetron reactive sputtering method for deposition of targetmaterial on a substrate, comprising, in combination: providing a vacuumchamber comprising a workpiece mount for mounting a substrate within thevacuum chamber and for spinning the substrate about an axis duringsputtering; providing a plurality of cathode assemblies mounted to thevacuum chamber and each cathode assembly comprising: a target ofsputterable material having an at least partially exposed planarsputtering surface, a magnetic field source having a central axisextending perpendicular to a major surface of magnets in the magneticfield source, and a target support configured to support the target andcomprising a drive mechanism operative to be actuated to rotate thetarget about a target axis fixed with respect to the vacuum chamberduring sputtering; wherein each cathode assembly is configured forlong-throw sputtering of target material onto the substrate; mounting aworkpiece to the workpiece mount; at least partially evacuating thevacuum chamber and then providing a sputtering gas in the vacuumchamber; and sputtering target material from the target onto thesubstrate with dual alternating cathode DC reactive sputtering,comprising supplying power to initiate and maintain a sputtering plasma,supplying power to actuate the drive mechanism to move the substantiallyplanar sputtering surface of the target relative to the vacuum chamberduring the sputtering, spinning the substrate during sputtering, andmaintaining the magnetic field source substantially stationary relativeto the vacuum chamber during the sputtering, wherein the central axisextends in a direction perpendicular to the planar sputtering surfaceand at an acute angle with respect to the axis about which the substratespins.
 22. The DC magnetron reactive sputtering method of claim 21, fordeposition of target material on a substrate, wherein the drivemechanism rotates the substantially planar sputtering surface in theplane of the sputtering surface.
 23. The DC magnetron reactivesputtering method of claim 21, for deposition of target material on asubstrate, wherein the magnetic field source comprises a magnet arrayand the drive mechanism moves the substantially planar sputteringsurface of the target relative to the magnet array.
 24. The DC magnetronreactive sputtering method of claim 23, for deposition of targetmaterial on a substrate, wherein the drive mechanism moves thesubstantially planar sputtering surface of the target relative to themagnet array and the vacuum chamber.
 25. The DC magnetron reactivesputtering method of claim 24, for deposition of target material on asubstrate, wherein the magnet array is substantially stationary relativeto the vacuum chamber during sputtering.
 26. The DC magnetron reactivesputtering method of claim 21, wherein the plurality of cathodeassemblies includes a pair of cathode assemblies configured for dualalternating cathode DC reactive sputtering.
 27. The DC magnetronreactive sputtering method of claim 21, wherein a ration of an area of aplanar erosion surface of the target to an area of a footprint of themagnetic field source is greater than 3.0.
 28. A DC magnetron reactivesputtering system comprising, in combination: a vacuum chambercomprising a workpiece mount for mounting a substrate within the vacuumchamber and for spinning the substrate about an axis during sputtering,and a plurality of cathode assemblies configured for DC reactivesputtering, each cathode assembly comprising: a target comprisingsputterable material having an at least partially exposed planarsputtering surface, a target support configured to support the target inthe vacuum chamber and rotate the target relative to the vacuum chamberabout an axis fixed with respect to the vacuum chamber duringsputtering, and a magnetic field source having a central axis, andcomprising a magnet array, the central axis extending perpendicular to amajor surface of each magnet in the array, wherein the magnet array isoperative to dither the magnet array during sputtering, and wherein thecathode assembly is configured for long-throw sputtering of targetmaterial onto the substrate, and wherein the central axis of the magnetarray extends in a direction perpendicular to the planar sputteringsurface and at an acute angle with respect to the axis about which thesubstrate spins.
 29. The DC magnetron reactive sputtering system ofclaim 1, wherein the target is conically shaped.
 30. The DC magnetronreactive sputtering system of claim 29, wherein the magnet array followsa curve of a cone.